1. Technical Field
The invention relates to decorative, imitation candles and, more particularly, to an imitation candle simulating a lighted wick.
2. Description of the Problem
Numerous manufacturers have attempted to meet a demand for a flameless, candle like luminary using electrical illumination. There are many imitation candles available that use incandescent lamps or LEDs as a light source. These devices address people's concern with having an open flame indoors. Most of these devices try to implement the appearance of a realistic flame using a specially shaped bulb or lens that is exposed to view. Typically, the bulb or lens sits on top of a thin cylindrical sleeve, which is shaped and colored to resemble a candle. The results are typically disappointing, especially when these devices are not illuminated. The visible, flame shaped artificial light source draws attention to the fact that the device is an imitation candle. The result can look more like a caricature of a candle than a real candle. The color of incandescent light can leave something to be desired in many candles as well.
In addition, there are also imitation candles available that utilize one or more very small incandescent lamps or LEDs as the light source which do not place the light source inside a flame shaped structure. Examples exist of imitation candles which have a deep well on the top to simulate a candle that has been burning for some time. As these light sources are relatively small they can be concealed within the deep well of the artificial candle. From most viewing angles, the wall of the artificial candle would be between the light source and the viewers eye. At these viewing angles there is no artificial flame structure visible that would detract from the candle's realism. However, when viewed from above, the small light source (or sources) are readily visible and reveal that the candle is an imitation. It would be desirable to provide an imitation candle that is viewable from the side or above without revealing an obvious artificial light source.
A key visual element of a real flame is a rather intense area of light. When the flame is viewed directly, in a darkened environment, the flame can become a source of glare for an eye accommodated to scotopic vision. Eyes adjusted to darkness cannot tolerate the large contrast in brightness and as a result, the physical outline of the flame is often lost to the eyes in the glare. In the case of artificial flame structures, the outer surface is often frosted so that the flame structure is itself lit up. By spreading the light from the artificial light source across a larger surface area, the intensity of light across the surface is much less than that from an illumination source. Because of this lack of point source intensity, the brain does not interpret the flame structure as a real flame, but still comprehends the structure. Incandescent lamps that have clear glass flame structures reveal an intense filament, but the filaments are generally linear, detracting from their appearance. The glass, though clear, may still be visible as well.
U.S. Pat. No. 6,616,308, which is incorporated herein by reference, teaches an imitation candle configured to diminish any expectation on the part of an observer of seeing an open flame. Many of the typical deficiencies found in imitation candles are addressed in the '308 patent. The flame structure is eliminated and so does not detract from the candle's realism when not illuminated. In addition, the candle's structure is such that from most viewing angles the observer would not expect to have a direct view of the flame and so the lack of a flame when illuminated does not detract from the candle's realism. When the candle is off and viewed from above, there is no visible bulb or other structure to reveal that the candle is artificial. An imitation wick, visible when the candle is viewed from above, can be used to complete the illusion that the candle is real. However, when the imitation candle of the '308 patent is on and viewed from above, there is no bright source of light at the end of the wick as would be expected in a real candle. It would be desirable to provide an artificial candle with an artificial wick that when viewed from the side or above, does not reveal an obvious light source or other structure that would reveal that the candle is artificial, while at the same time providing a bright source of light at the tip of the wick when the candle is on.
One approach to creating a realistic illusion of a flame is disclosed in U.S. patent application Ser. No. 10/844,075, filed 12 May 2004 (now U.S. Pat. No. 7,093,961 and assigned to the assignee of the present application), which is incorporated herein by reference. This application discloses an LED hidden within a fixture above an imitation candle body. Light emitted by the LED is directed to illuminate the candle body and wick from above. The LED is driven by a variable current to produce flickering light. The imitation wick has a reflective tip which reflects the incident light to create a small bright spot. The bright spot at the tip of the wick is sufficiently bright that even though the light source may be flickering, the intensity remains strong enough that the eye sees the resultant glare but cannot see the change in intensity of the spot. At the same time, light shines past the wick and onto the candle body where it is diffused throughout a relatively large volume. The light intensities within the candle body are much lower resulting in a dramatic, flickering effect.
For standalone imitation candles that are not housed in a permanent fixture, the approach of the '075 application is more difficult to effect since there is no convenient place to hide the LED but within the candle body itself. An approach to creating a realistic illusion of a flame that does not require a permanent fixture is disclosed in U.S. patent application Ser. No. 11/053,397, filed 31 Mar. 2005 (now U.S. Pat. No. 7,360,935 and assigned to the assignee of the present application), which is incorporated herein by reference. This application discloses an LED hidden within an imitation candle body as in the '308 patent. One end of a fiber optic wick is positioned in close proximity to the LED and captures part of the emitted light. The captured light is directed to the upper, exposed end of the fiber optic wick which then glows brightly in response. The majority of the length of the artificial wick is covered by a dark material, so the overall visual effect is that of a real wick, the tip of which is glowing brightly. The candle can be viewed from the side or above without revealing any light sources or artificial structures that detract from the candles realism.
While the approach described in the '397 application is effective, it may be desirable to produce a light intensity at the tip of the wick that is even brighter than that which can be achieved using a fiber optic wick to transmit a portion of the light emitted by the LED. It would be desirable to place the light source at the tip of the wick for maximum brightness while at the same time incorporating the light source and its support structure into an artificial wick that does not detract from the candle's realism when the candle is viewed from the side or from above.
The present inventors are familiar as well with a decorative, miniature Christmas tree, which is constructed from wires which terminate in surface mount technology light emitting diodes. The wires are soldered to the SMT LEDs, which are scattered about the tree producing the effect of a fully lighted tree.